bcache: Pull on disk data structures out into a separate header

Now, the on disk data structures are in a header that can be exported to
userspace - and having them all centralized is nice too.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

1 files changed, 373 insertions, 0 deletions

diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h
new file mode 100644
index 000000000000..164a7e263988
--- /dev/null
+++ b/include/uapi/linux/bcache.h
@@ -0,0 +1,373 @@
+#ifndef _LINUX_BCACHE_H
+#define _LINUX_BCACHE_H
+
+/*
+ * Bcache on disk data structures
+ */
+
+#include <asm/types.h>
+
+#define BITMASK(name, type, field, offset, size)		\
+static inline __u64 name(const type *k)				\
+{ return (k->field >> offset) & ~(~0ULL << size); }		\
+								\
+static inline void SET_##name(type *k, __u64 v)			\
+{								\
+	k->field &= ~(~(~0ULL << size) << offset);		\
+	k->field |= (v & ~(~0ULL << size)) << offset;		\
+}
+
+/* Btree keys - all units are in sectors */
+
+struct bkey {
+	__u64	high;
+	__u64	low;
+	__u64	ptr[];
+};
+
+#define KEY_FIELD(name, field, offset, size)				\
+	BITMASK(name, struct bkey, field, offset, size)
+
+#define PTR_FIELD(name, offset, size)					\
+static inline __u64 name(const struct bkey *k, unsigned i)		\
+{ return (k->ptr[i] >> offset) & ~(~0ULL << size); }			\
+									\
+static inline void SET_##name(struct bkey *k, unsigned i, __u64 v)	\
+{									\
+	k->ptr[i] &= ~(~(~0ULL << size) << offset);			\
+	k->ptr[i] |= (v & ~(~0ULL << size)) << offset;			\
+}
+
+#define KEY_SIZE_BITS		16
+
+KEY_FIELD(KEY_PTRS,	high, 60, 3)
+KEY_FIELD(HEADER_SIZE,	high, 58, 2)
+KEY_FIELD(KEY_CSUM,	high, 56, 2)
+KEY_FIELD(KEY_PINNED,	high, 55, 1)
+KEY_FIELD(KEY_DIRTY,	high, 36, 1)
+
+KEY_FIELD(KEY_SIZE,	high, 20, KEY_SIZE_BITS)
+KEY_FIELD(KEY_INODE,	high, 0,  20)
+
+/* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */
+
+static inline __u64 KEY_OFFSET(const struct bkey *k)
+{
+	return k->low;
+}
+
+static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
+{
+	k->low = v;
+}
+
+/*
+ * The high bit being set is a relic from when we used it to do binary
+ * searches - it told you where a key started. It's not used anymore,
+ * and can probably be safely dropped.
+ */
+#define KEY(inode, offset, size)					\
+((struct bkey) {							\
+	.high = (1ULL << 63) | ((__u64) (size) << 20) | (inode),	\
+	.low = (offset)							\
+})
+
+#define ZERO_KEY			KEY(0, 0, 0)
+
+#define MAX_KEY_INODE			(~(~0 << 20))
+#define MAX_KEY_OFFSET			(~0ULL >> 1)
+#define MAX_KEY				KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)
+
+#define KEY_START(k)			(KEY_OFFSET(k) - KEY_SIZE(k))
+#define START_KEY(k)			KEY(KEY_INODE(k), KEY_START(k), 0)
+
+#define PTR_DEV_BITS			12
+
+PTR_FIELD(PTR_DEV,			51, PTR_DEV_BITS)
+PTR_FIELD(PTR_OFFSET,			8,  43)
+PTR_FIELD(PTR_GEN,			0,  8)
+
+#define PTR_CHECK_DEV			((1 << PTR_DEV_BITS) - 1)
+
+#define PTR(gen, offset, dev)						\
+	((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
+
+/* Bkey utility code */
+
+static inline unsigned long bkey_u64s(const struct bkey *k)
+{
+	return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
+}
+
+static inline unsigned long bkey_bytes(const struct bkey *k)
+{
+	return bkey_u64s(k) * sizeof(__u64);
+}
+
+#define bkey_copy(_dest, _src)	memcpy(_dest, _src, bkey_bytes(_src))
+
+static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
+{
+	SET_KEY_INODE(dest, KEY_INODE(src));
+	SET_KEY_OFFSET(dest, KEY_OFFSET(src));
+}
+
+static inline struct bkey *bkey_next(const struct bkey *k)
+{
+	__u64 *d = (void *) k;
+	return (struct bkey *) (d + bkey_u64s(k));
+}
+
+static inline struct bkey *bkey_last(const struct bkey *k, unsigned nr_keys)
+{
+	__u64 *d = (void *) k;
+	return (struct bkey *) (d + nr_keys);
+}
+/* Enough for a key with 6 pointers */
+#define BKEY_PAD		8
+
+#define BKEY_PADDED(key)					\
+	union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }
+
+/* Superblock */
+
+/* Version 0: Cache device
+ * Version 1: Backing device
+ * Version 2: Seed pointer into btree node checksum
+ * Version 3: Cache device with new UUID format
+ * Version 4: Backing device with data offset
+ */
+#define BCACHE_SB_VERSION_CDEV		0
+#define BCACHE_SB_VERSION_BDEV		1
+#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
+#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
+#define BCACHE_SB_MAX_VERSION		4
+
+#define SB_SECTOR			8
+#define SB_SIZE				4096
+#define SB_LABEL_SIZE			32
+#define SB_JOURNAL_BUCKETS		256U
+/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
+#define MAX_CACHES_PER_SET		8
+
+#define BDEV_DATA_START_DEFAULT		16	/* sectors */
+
+struct cache_sb {
+	__u64			csum;
+	__u64			offset;	/* sector where this sb was written */
+	__u64			version;
+
+	__u8			magic[16];
+
+	__u8			uuid[16];
+	union {
+		__u8		set_uuid[16];
+		__u64		set_magic;
+	};
+	__u8			label[SB_LABEL_SIZE];
+
+	__u64			flags;
+	__u64			seq;
+	__u64			pad[8];
+
+	union {
+	struct {
+		/* Cache devices */
+		__u64		nbuckets;	/* device size */
+
+		__u16		block_size;	/* sectors */
+		__u16		bucket_size;	/* sectors */
+
+		__u16		nr_in_set;
+		__u16		nr_this_dev;
+	};
+	struct {
+		/* Backing devices */
+		__u64		data_offset;
+
+		/*
+		 * block_size from the cache device section is still used by
+		 * backing devices, so don't add anything here until we fix
+		 * things to not need it for backing devices anymore
+		 */
+	};
+	};
+
+	__u32			last_mount;	/* time_t */
+
+	__u16			first_bucket;
+	union {
+		__u16		njournal_buckets;
+		__u16		keys;
+	};
+	__u64			d[SB_JOURNAL_BUCKETS];	/* journal buckets */
+};
+
+static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
+{
+	return sb->version == BCACHE_SB_VERSION_BDEV
+		|| sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
+}
+
+BITMASK(CACHE_SYNC,			struct cache_sb, flags, 0, 1);
+BITMASK(CACHE_DISCARD,			struct cache_sb, flags, 1, 1);
+BITMASK(CACHE_REPLACEMENT,		struct cache_sb, flags, 2, 3);
+#define CACHE_REPLACEMENT_LRU		0U
+#define CACHE_REPLACEMENT_FIFO		1U
+#define CACHE_REPLACEMENT_RANDOM	2U
+
+BITMASK(BDEV_CACHE_MODE,		struct cache_sb, flags, 0, 4);
+#define CACHE_MODE_WRITETHROUGH		0U
+#define CACHE_MODE_WRITEBACK		1U
+#define CACHE_MODE_WRITEAROUND		2U
+#define CACHE_MODE_NONE			3U
+BITMASK(BDEV_STATE,			struct cache_sb, flags, 61, 2);
+#define BDEV_STATE_NONE			0U
+#define BDEV_STATE_CLEAN		1U
+#define BDEV_STATE_DIRTY		2U
+#define BDEV_STATE_STALE		3U
+
+/*
+ * Magic numbers
+ *
+ * The various other data structures have their own magic numbers, which are
+ * xored with the first part of the cache set's UUID
+ */
+
+#define JSET_MAGIC			0x245235c1a3625032ULL
+#define PSET_MAGIC			0x6750e15f87337f91ULL
+#define BSET_MAGIC			0x90135c78b99e07f5ULL
+
+static inline __u64 jset_magic(struct cache_sb *sb)
+{
+	return sb->set_magic ^ JSET_MAGIC;
+}
+
+static inline __u64 pset_magic(struct cache_sb *sb)
+{
+	return sb->set_magic ^ PSET_MAGIC;
+}
+
+static inline __u64 bset_magic(struct cache_sb *sb)
+{
+	return sb->set_magic ^ BSET_MAGIC;
+}
+
+/*
+ * Journal
+ *
+ * On disk format for a journal entry:
+ * seq is monotonically increasing; every journal entry has its own unique
+ * sequence number.
+ *
+ * last_seq is the oldest journal entry that still has keys the btree hasn't
+ * flushed to disk yet.
+ *
+ * version is for on disk format changes.
+ */
+
+#define BCACHE_JSET_VERSION_UUIDv1	1
+#define BCACHE_JSET_VERSION_UUID	1	/* Always latest UUID format */
+#define BCACHE_JSET_VERSION		1
+
+struct jset {
+	__u64			csum;
+	__u64			magic;
+	__u64			seq;
+	__u32			version;
+	__u32			keys;
+
+	__u64			last_seq;
+
+	BKEY_PADDED(uuid_bucket);
+	BKEY_PADDED(btree_root);
+	__u16			btree_level;
+	__u16			pad[3];
+
+	__u64			prio_bucket[MAX_CACHES_PER_SET];
+
+	union {
+		struct bkey	start[0];
+		__u64		d[0];
+	};
+};
+
+/* Bucket prios/gens */
+
+struct prio_set {
+	__u64			csum;
+	__u64			magic;
+	__u64			seq;
+	__u32			version;
+	__u32			pad;
+
+	__u64			next_bucket;
+
+	struct bucket_disk {
+		__u16		prio;
+		__u8		gen;
+	} __attribute((packed)) data[];
+};
+
+/* UUIDS - per backing device/flash only volume metadata */
+
+struct uuid_entry {
+	union {
+		struct {
+			__u8	uuid[16];
+			__u8	label[32];
+			__u32	first_reg;
+			__u32	last_reg;
+			__u32	invalidated;
+
+			__u32	flags;
+			/* Size of flash only volumes */
+			__u64	sectors;
+		};
+
+		__u8		pad[128];
+	};
+};
+
+BITMASK(UUID_FLASH_ONLY,	struct uuid_entry, flags, 0, 1);
+
+/* Btree nodes */
+
+/* Version 1: Seed pointer into btree node checksum
+ */
+#define BCACHE_BSET_CSUM		1
+#define BCACHE_BSET_VERSION		1
+
+/*
+ * Btree nodes
+ *
+ * On disk a btree node is a list/log of these; within each set the keys are
+ * sorted
+ */
+struct bset {
+	__u64			csum;
+	__u64			magic;
+	__u64			seq;
+	__u32			version;
+	__u32			keys;
+
+	union {
+		struct bkey	start[0];
+		__u64		d[0];
+	};
+};
+
+/* OBSOLETE */
+
+/* UUIDS - per backing device/flash only volume metadata */
+
+struct uuid_entry_v0 {
+	__u8		uuid[16];
+	__u8		label[32];
+	__u32		first_reg;
+	__u32		last_reg;
+	__u32		invalidated;
+	__u32		pad;
+};
+
+#endif /* _LINUX_BCACHE_H */